It is known, when analyzing any type of material, to use optical emission spectroscopy on laser-induced plasma. This elementary analytical technique is known as LIBS (Laser-Induced Breakdown Spectroscopy). The principle is to analyze the lines emitted by a material to be analyzed as a function of their intensity. This analysis is generally done line by line, which is relatively painstaking. When a method of this type is used without access to specific databases, it is impossible to study the correlation of the various elements present in the sample with one another. In fact, the existing databases, for example the databases like those provided by the American agency NIST (National Institute of Standards and Technology), contain results recorded with different measuring devices and in different formats; therefore, these databases cannot be used to perform intensity comparisons between several elements, since not all measuring devices have the same influence on the readings taken.
Furthermore, when wishing to use a method like LIBS for quantitative analysis, it may be necessary to create a calibration curve for the detection device used, in order to compensate for any influence this device may have on the measurements obtained. The known methods for obtaining these calibration curves are generally such that the curves depend on the matrix used, i.e. a liquid, solid or gaseous matrix, and it is therefore necessary to recalculate them for each matrix analyzed. Thus, if a calibration curve is created for solutions, i.e. for a liquid matrix, this curve is not necessarily valid for measurements performed on gaseous or solid samples.
Methods for eliminating these matrix effects have been proposed, but these methods are based on physical interpretations of the results and do not account for the problems associated with testing, such as spectral saturation or simultaneous analyses of major and trace elements.
It is also known to create a database on liquid solutions and to use this database for the qualitative analysis of any type of sample, though not for quantitative analysis.